I have a question about the period when Magmaw is about to be mountable and when the Head is finally exposed, and the attacks castable around that time.

This is how I imagine the highest dps situation should work:

Get a fresh Rake and extended Rip (with 3 Shreds) off on the body and then either energy pool for the head, or if TF is up, continue Shredding till the head is exposed, target switch, FF, Beserk/TF macro, take a pot/pop trinket and do my normal rotation. Finally, just a few seconds before the "Point of Vulnerability" buff wears off, do a final Rake and Rip on the Head (even if not at 5 points).

This is what actually happens:

I dps the heroic add, then at the last minute switch to boss and Rake and Rip the body, then whilst they are trying to chain him, I find myself unable to shred at all. I go close to max energy before I realise this. I then panic and Mangle spam to use energy up. The head then drops and I lose a second or two trying to target the damn thing, and then waste my first GCD on a FF. I do my normal rotation and then when Point of Vulnerability is about to finish, I find myself on 3 combos, but Rip anyway, as it's better than nothing.

So, aside from telling me not to suck so much , any other tips for maximising this fight? How come when he is mountable he is suddenly unShredable? Has anyone else noticed this? It seems to last for 5-10 seconds and I find it frustrating.

A friend of mine uses the glyph of FB for heroic Magmaw. What he does is wait for the heroic add to hit the BiTW phase, and then he refreshes Rake and uses up any remaining combo points on an FB to refresh Rip. He then switches back to Magmaw - which gives him extra time to get his DoTs back up while the rest of the raid finishes off the add.

Given that using the glyph of FB is very close to being dps neutral - this is an interesting and clever way to utilize it. I am sure others will have some useful suggestions also. Most weeks of late I have been tanking the fight, so I don't have a lot to add myself.

You overrate DI these days LK. As for Magmaw, well there are two ways of going about it and it really depends on your aim. If you desire simply to kill the boss and this is a desire shared by your guild then it is most optimal for you to derp on the boss as if your entire guild is attacking the adds you will have problems getting a rip up on them (the same shitty ramp up applies to rets and enhancement shamans). If you can't shred then ask your tanks to tank the boss up against the wall on the left or right. You then stand at the opposite wall and derp the boss.

If you have to attack the adds, this is about the only place I would say running out to get a fc off is beneficial. This is due to wanting to get a rip up and then immediately switching back to the boss.

If your aim is to get a ranking then you have to be a penis and swipe parasites. The top logs are people entirely on parasites which is completely fucking useless but this is the game now that swipe has been buffed.

Honest suggestion is to offer to tank the constructs as bears do fairly good damage while doing this and you won't want to eviscerate yourself.

I always do Magmaw hc in my bearcat offspec to eat Magmaws mangles in bear form. Basically I dps in cat form until about 10 sec before mangle. Then I switch to bear, taunt < 5 sec before mangle and pop a cooldown. When Magmaw throws me off again the head is down and I continue dps'ing.

This makes me feel more usefull You can do pretty good dmg even while doing this.